Transcript Session 6

Master Production Scheduling
(MPS) – Basic Techniques
http://www.pom.edu/mpc/lectures_in_manufacturing_planning.htm
lecture session 6
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MPS: Role in the MPC System
MPS Defined
MPS Approaches
Single Level MPS Time-Phased Record
Customer Order Processing
Rolling through Time (Transactions)
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Manufacturing Planning and Control System
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MPS Defined
• Anticipated Build Schedule – a statement of production not
market demand
• The MPS is:
– Stated in terms of product specifications
– Concerned with product mix while Sales and
Operations Planning is concerned with volume
• The MPS is the basis for:
– Making customer delivery promises
– Utilizing plant capacity effectively
– Attaining the strategic objectives in the sales and
operations plan
– Resolving trade-offs between manufacturing and
marketing
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MPS Approaches
• Make – to – Stock
• Make – to – Order
• Assemble – to – Order
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Single Level MPS Record Example
• The Zero Manufacturing Company ships Product A from the firm's plant
warehouse to satisfy East Coast demand. Currently, the sales forecast for
Product A at the Murphysboro plant is 30 units per period.
• Product A is considered a make-to-stock item.
– Plant warehouse on hand inventory = 50 units
– Safety Stock = 10 units
– Lot Size = L4L
– Open Order for 30 units due in period 1
• The master production scheduler has heard that an MRP record which
uses the forecast for gross requirements and has a lead time of zero can
be used for master production scheduling. Complete the following MRP
record. How can this be used for master production scheduling?
Product A
Gross requirements
Scheduled receipts
Projected available balance
Planned order release
Q = lot for lot; LT = 0; SS = 10
1
2
Period
3
4
5
6
5
Single Level MPS Record Processing
Product A
Gross requirements
Scheduled receipts
Projected available balance 50
Planned order release
Q = lot for lot; LT = 0; SS = 10
1
30
30
50
2
30
20
Period
3
4
30 30
5
30
6
30
10
20
10
30
10
30
10
30
One way viewing an MPS is as the set of planned order
releases and scheduled receipts in a record such as
above. The problem is that any errors in forecast will be
reflected in the on-hand balance. All changes will come in
the planned orders. Use of firm planned orders will
reduce this instability.
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Customer Order Promising Example
The MPS planner at Murphy Motors uses MPS
time-phased records for planning end item
production. The planner is currently working
on a schedule for the P24. The production lot
size is 70 and the safety stock is 5.
Item: P24
Forecast
Orders
Available
Available to promise
MPS (completion)
On hand = 20, MPS Lot Size = 70
Period
1
2
3
4
5
6
7
8
30 30 30 40 40 40 45 45
13
8
4
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Customer Order Promising
Example
a. Complete the MPS time-phased record for P24.
b. Can Murphy accept the following orders?
Update the MPS time-phased record for
accepted orders.
Order Amount Desired Period
1
40
4
2
30
6
3
30
2
4
25
3
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Customer Order Processing
Procedure
a.
b.
Period
Item: P24
1 2 3 4 5 6
Forecast
30 30 30 40 40 40
Orders
13 8 4
Available
60 30 70 30 60 20
Available to promise
69
66
70
MPS (Completion)
70
70
70
On hand = 20, MPS lot size = 70
Order Amount Desired Period
1
40
4
2
30
6
3
30
2
4
25
3
7 8
45 45
45 70
70 70
70 70
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Customer Order Processing Procedure
Order Amount Desired Period Accept (Y or N)
1
40
4
Y
2
30
6
Y
b.
3
30
2
Y
4
25
3
Y
Item: P24
1
2
3
Forecast
30
30
30
Orders
13
38
29
Available
60
22
62
Available to promise 39
1
MPS (Completion)
70
70
On hand = 20, MPS lot size = 70
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Period
4
5
40
40
40
22
52
40
70
6
40
30
12
7
45
8
45
37
70
70
62
70
70
The convention of the greater of forecast or orders is
used in determining the projected available balance.
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Rolling Through Time –
Transactions Example
The following MPS time phased record has been
prepared at the start of period 1.
Period
Item: Smell fresh
1 2 3 4 5 6
Forecast
20 20 20 30 30 30
Orders
5 3 2
Available
50 30 10 30 50 20
Available to promise 60
50 50
MPS (Completion) 50
50 50
On hand = 20, MPS lot size = 50
7 8
30 30
40 10
50
50
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Rolling Through Time –
Transactions Example
The following events occurred during period 1:
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Actual demand during period 1 was 25 units.
Marketing forecasted that 40 units would be
needed for period 9.
An order for 10 in period 2 was accepted.
An order for 20 in period 4 was accepted.
An order for 6 in period 3 was accepted.
The MPS in period 1 was produced as
planned.
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Rolling through Time -Transactions/ Processing
b. Update the record below after rolling through time.
Smell fresh
Period
Forecast
Orders
Available
Available to promise
MPS (Completion)
On Hand = 45, MPS
2 3
20 20
13 8
25 5
24
4 5 6
30 30 30
20
25 45 15
30 50
50 50
lot size = 50
Beginning On Hand Period 1 = 20
Period 1 Actual Demand
= -25
MPS Receipt Into Stock
=+50
Beginning on Hand Period 2
= 45
7 8
9
30 30 40
35
50
50
5 15
50
50
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